1. Field of the Invention
The present invention relates to a method adapted for production of a rubber product molded from a novel granular master batch, especially, a rubber-molded product such as a weather strip.
2. Description of the Related Art
Heretofore, for example, an extrudent product such as a weather strip was produced as follows (see “The ABC of Rubber Technology” edited by The Society of Rubber Industry, Japan, Tokai Branch, pp.209–210, 214–215, Apr. 1, 1973).
(1) Kneading in Banbury Mixer:
(i) Veil-like raw rubber of EPDM is cut into pieces with a predetermined size and the pieces are put into a Banbury mixer.
(ii) Auxiliary materials such as stearic acid, zinc oxide, and calcium oxide are put into the mixer.
(iii) A half amount of carbon black is put into the mixer.
(iv) A full amount of process oil is put into the mixer.
(v) The residual amount of carbon black is put into the mixer.
(2) Kneading of Vulcanizing Chemicals in Open Roll Mill:
While the kneaded rubber taken out from the Banbury mixer is wound on a cooled roll, vulcanizing chemicals (a vulcanizing agent and a vulcanization accelerator) are added into and kneaded with the kneaded rubber.
(3) Treatment after Kneading:
The rubber compound which has been already kneaded and compounded is partially taken out from the roll, cooled with water, subjected to an anti-adhesion treatment and preserved.
(4) Extrusion Molding:
The rubber compound is pre-plasticized by a charge roll, extracted in the form of a tape and supplied to a hopper continuously.
In this manner, the kneading operation for preparing the rubber compound is performed by a batch process or a manual process. The number of man-hour becomes therefore large, so that the number of steps for producing the extrudent such as a weather strip becomes large.